1. Field of the Invention
The present invention relates to a head suspension for a hard disk drive incorporated in an information or data processing apparatus such as a computer.
2. Description of the Related Art
In general, a head suspension for a hard disk drive includes a base plate, a load beam extending from the base plate toward a head, a flexure, and the like. The load beam is conventionally made of a stainless steel such as SUS304 or SUS301 (Japanese Industrial Standard) with a plate thickness of about 20 μm to 100 μm. The flexure is conventionally formed by applying an insulating material layer (polyimide) and an electrically conductive layer (copper) on a base material made of a stainless steel plate (SUS304) with a plate thickness of 20 μm or a proper resilient material using a laminating process or a usual photolithographic process.
FIG. 5 shows a chain product of flexures. The chain product has a plurality of flexures 101. Each flexure 101 includes a base material and electrically conductive layers formed on the base material. Respective flexures 101 are mutually connected by coupling portions 103 of base materials. At a time of assembling a head suspension, each flexure 101 is cut off at the coupling portion 103 as a single part stacked on each base plate and each load beam, and these stacked members are welded and fixed at their predetermined spots by, for example, laser welding. After assembled, ultrasonic washing is performed on an assembled head suspension.
FIG. 6 is an enlarged plan view partly showing an assembled head suspension.
As described above, the flexure 101 is cut at the coupling portion 103 to constitute the single part. The cut coupling portion 103 remains on each side of the flexure to form a cut portion 105. After assembling, the cut portion 105 overlaps a rigid part 109 of a load beam 107 as shown in FIG. 6. In this state, the cut portions 105 serves as free ends which can be freely supported to the rigid part 109.
Therefore, in the ultrasonic washing after the completion of the assembly, the cut portions 105 vibrate or flutter to repeatedly contact with a surface of the rigid part 109. This causes color change or discoloration at the contacting portions of the rigid part 109. Especially, the cut portion 105 has burrs, due to cutting, that are directed toward the rigid part 109, so that color change tends to become significant.
In a case of the flexure 101 including a curved portion curving sideward on the base plate, the curved portion vibrates or flutters to repeatedly contact with the base plate side to color-change during the ultrasonic washing.
To solve the problem, a chain product of flexures 101A as shown in FIG. 7 is adopted. The chain product has coupling portions 103A. The coupling portions 103A is formed to be slightly long as compared with the coupling portions 103 of FIG. 6, to set cut portions 105A of FIG. 8 to be longer than the cut portions 105 of FIG. 6, so that free ends of the cut portions 105A are positioned outside the rigid part 109. In this case, the cut portions 105A, particularly, the free ends do not contact with the rigid part 109, when the cut portions 105A vibrate or flutter. Therefore, color change due to vibration contact of the flexure with the rigid part 109 during the ultrasonic washing can be suppressed.
However, this structure involves a restraint for layout in view of base material formation of the flexure, and thereby design with high flexibility can not be achieved.
Additionally, this structure can not suppress the color change at the curved portion, either. For the details of the above-mentioned related art, Japanese Unexamined Patent Application Publication No. 2002-237013 can be referred to.